Microscopic dynamics of stress relaxation in a nanocolloidal soft glass
Microscopic dynamics of stress relaxation in a nanocolloidal soft glass
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DOI：
10.1103/physrevmaterials.4.035602
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发表时间：
2020-03-06
影响因子：
3.4
通讯作者：
Leheny, Robert L.
中科院分区：
文献类型：
--
作者：
Chen, Yihao;Rogers, Simon A.;Leheny, Robert L.
我们报道了用原位流变仪进行的X射线光子相关谱(XPCS)实验，该实验是在一个软玻璃上进行的，该软玻璃由带电的二氧化硅纳米颗粒的浓缩悬浮液受到阶跃应变引起的屈服和流动。XPCS测量表征了玻璃中颗粒尺度和中尺度的运动，这些运动是台阶应变后宏观应力高度持久衰减的基础。这些动力学是各向异性的，粒子沿着前一个切变的方向缓慢对流运动，持续时间惊人地长，并伴随着垂直(涡度)方向的间歇运动。通过粒子集体运动的特征速度和应力衰减率之间的幂函数标度，证明了对流动力学和应力松弛之间的密切对应。
We report x-ray photon correlation spectroscopy (XPCS) experiments with in situ rheometry performed on a soft glass composed of a concentrated suspension of charged silica nanoparticles subjected to step strains that induce yielding and flow. The XPCS measurements characterize the particle-scale and mesoscale motions within the glass that underlie the highly protracted decay of the macroscopic stress following the step strains. These dynamics are anisotropic, with slow, convective particle motion along the direction of the preceding shear that persists for surprisingly large times and that is accompanied by intermittent motion in the perpendicular (vorticity) direction. A close correspondence between the convective dynamics and stress relaxation is demonstrated by power-law scaling between the characteristic velocity of the collective particle motion and the rate of stress decay.